[ 3.8.y.z extended stable ] Patch "drm/radeon/atom: workaround vbios bug in transmitter table on rs880" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    drm/radeon/atom: workaround vbios bug in transmitter table on rs880

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.11.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 1ec8cfa3fad213c7096139134fa329236cbc85a5 Mon Sep 17 00:00:00 2001
From: Alex Deucher <alexander.deucher at amd.com>
Date: Mon, 9 Sep 2013 10:54:22 -0400
Subject: drm/radeon/atom: workaround vbios bug in transmitter table on rs880
 (v2)

commit 91f3a6aaf280294b07c05dfe606e6c27b7ba3c72 upstream.

The OUTPUT_ENABLE action jumps past the point in the coder where
the data_offset is set on certain rs780 cards.  This worked
previously because the OUTPUT_ENABLE action is always called
immediately after the ENABLE action so the data_offset remained
set.  In 6f8bbaf568c7f2c497558bfd04654c0b9841ad57
(drm/radeon/atom: initialize more atom interpretor elements to 0),
we explictly reset data_offset to 0 between atom calls which then
caused this to fail.  The fix is to just skip calling the
OUTPUT_ENABLE action on the problematic chipsets.  The ENABLE
action does the same thing and more.  Ultimately, we could
probably drop the OUTPUT_ENABLE action all together on DCE3
asics.

fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=60791

v2: only rs880 seems to be affected

Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/radeon/atombios_encoders.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
index 8efd7e2..3b681de 100644
--- a/drivers/gpu/drm/radeon/atombios_encoders.c
+++ b/drivers/gpu/drm/radeon/atombios_encoders.c
@@ -1636,8 +1636,12 @@ radeon_atom_encoder_dpms_dig(struct drm_encoder *encoder, int mode)
 			atombios_dig_encoder_setup(encoder, ATOM_ENABLE, 0);
 			atombios_dig_transmitter_setup(encoder, ATOM_TRANSMITTER_ACTION_SETUP, 0, 0);
 			atombios_dig_transmitter_setup(encoder, ATOM_TRANSMITTER_ACTION_ENABLE, 0, 0);
-			/* some early dce3.2 boards have a bug in their transmitter control table */
-			if ((rdev->family != CHIP_RV710) && (rdev->family != CHIP_RV730))
+			/* some dce3.x boards have a bug in their transmitter control table.
+			 * ACTION_ENABLE_OUTPUT can probably be dropped since ACTION_ENABLE
+			 * does the same thing and more.
+			 */
+			if ((rdev->family != CHIP_RV710) && (rdev->family != CHIP_RV730) &&
+			    (rdev->family != CHIP_RS880))
 				atombios_dig_transmitter_setup(encoder, ATOM_TRANSMITTER_ACTION_ENABLE_OUTPUT, 0, 0);
 		}
 		if (ENCODER_MODE_IS_DP(atombios_get_encoder_mode(encoder)) && connector) {
--
1.8.1.2